The present invention relates to aerobic decomposition of animal and other organic waste, such as sewage sludge, and more particularly concerns an agitating apparatus which aerates and rapidly intermixes organic material in a containing vessel.
It is known that organic waste material may be efficiently processed by providing an environment which enhances the growth of thermophilic bacteria in the waste product. One such process for aerobically decomposing organic waste material is disclosed in applicant's U.S. Pat. No. 4,139,640. According to the method in this mentioned patent, a quantity of undecomposed organic waste material is introduced into one end of an elongate composting vessel. This quantity of material is maintained in the vessel until the material attains a predetermined thermophilic temperature. This quantity of material is then agitated, intermixed and advanced to a succeeding station toward the opposite end of the vessel. The quantity of material is then once again maintained in a quiescent state until a succeeding quantity of material deposited at the end of the vessel vacated by the advanced quantity of material reaches a predetermined thermophilic temperature. Each quantity of material is repeatedly and intermittently mixingly advanced to a succeeding station and maintained in a quiescent state until the last deposited quantity reaches a predetermined thermophilic temperature. This process is continued until the quantity of material is ultimately discharged from the composting or containing vessel. Transfer of each of the quantities is achieved by way of an endless conveyor which is advanced into the bottommost level of an accumulation of organic material. The endless conveyor extracts or digs up the underside of the organic waste accumulation and advances it toward the next station.
"Digging" conveyors for aerobic decomposition vessels which are advanced into the bottommost level of an accumulation of organic material are well known in the art. For example, U.S. Pat. No. 3,451,799 discloses a conveyor which is pivotally transported by a carriage movably mounted atop a composting vessel. This pivoted conveyor is inclined to undercut an accumulation of organic waste material as the conveyor is longitudinally transported along the top of the containing vessel. A similar type of pivoted conveyor is shown in U.S. Pat. No. 3,438,740.
Another example of a "digging" conveyor is seen in U.S. Pat. No. 3,323,896. This conveyor interfaces with the organic material in a generally vertical plane. The conveyor carries elevator buckets for transporting organic material, the elevator, in turn, being carried by a carriage which is moved longitudinally atop the containing vessel. A conveyor of this general nature is also disclosed in U.S. Pat. No. 3,294,491.
While many of the prior art devices have proved to be commercially viable, they are not without their attendent disadvantages. Many of the prior art devices have, for example, been limited as to their speed of operation. Another disadvantage of the prior art devices is that they do not adequately break up and aerate the organic material as it is being advanced from one station to the next. Aeration of this type is extremely important when working with aerobic bacteria which requires oxygen.
It is thus an object of the present invention to provide an apparatus for agitating and intermixing aerobic thermophilical composting organic waste materials in a manner which intermixes the waste material with plentiful amounts of air.
It is another object of the present invention to provide an apparatus for agitating and intermixing aerobic thermophilical composted organic waste materials in a rapid and efficient manner.
It is a further object of the present invention to provide an apparatus for efficiently transferring organic waste material from one location to another in a containment vessel.